US4502929A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Corrosion protection method
Assignee: Tyco International Ltd Bermuda
•
Filing: 1982-07-29
•
Granted: 1985-03-05
•
Expires: 2002-07-29
Abstract
Abstract Methods of preventing corrosion in which current flows between the to-be-protected substrate and a distributed electrode whose electrochemically active surface is provided by an element which is composed of a conductive polymer and which is at least 500 microns thick. In one embodiment, the electrode is a flexible strip comprising a highly conductive core, e.g. of copper, and a conductive polymer element surrounding the core. In another embodiment, the electrode is a conductive polymer layer which conforms to the surface of the substrate but is separated from it by a layer of insulation.
Inventors
- 👤 Ray F. Stewart
- 👤 Michael Masia
- 👤 Albert B. Macknick
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 21:49
CPC Classifications
C; C23; C23F; C23F13/00; C23F13/02; F; F16; F16L; F16L58/00
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
137 words
A method of cathodically protecting an elongate, electrically conductive substrate which is buried in soil, which method comprises establishing a potential difference between the substrate as cathode and a distributed elongate anode which is buried in the soil adjacent to the substrate and spaced apart from the substrate by soil, the anode comprising a flexible strip comprising (1) a continuous elongate flexible metal core which has a resistance at 23° C. of less than 0.03 ohm/meter; and (2) an elongate element which (i) is in electrical contact with the core; (ii) is composed of a conductive polymer having an elongation of at least 10% and a resistivity at 23° of 0.1 to 10 3 ohm.cm; (iii) provides substantially the whole of the electrochemically active surface of the flexible strip; and (iv) is at least 500 microns thick.
Claim 2
Independent Claim
137 words
A method of cathodically protecting an elongate, electrically conductive substrate which is buried in soil, which method comprises establishing a potential difference between the substrate as cathode and a distributed elongate anode which is buried in the soil adjacent to the substrate and spaced apart from the substrate by soil, the anode comprising a flexible strip comprising (1) a continuous elongate flexible metal core which has a resistance at 23° C. of less than 0.03 ohm/meter; and (2) an elongate element which (i) is in electrical contact with the core; (ii) is composed of a conductive polymer having an elongation of at least 10% and a resistivity at 23° of 0.1 to 10 3 ohm.cm; (iii) provides substantially the whole of the electrochemically active surface of the flexible strip; and (iv) is at least 500 microns thick.
Claim 3
Dependent Claim
17 words
A method according to claim 1 wherein the conductive polymer element is at least 1000 microns thick.
Claim 4
Dependent Claim
29 words
A method according to claim 1 wherein the anode has Quasi-Tafel Constant of at least 300 millivolts/decade over a current density range of 1 to 500 microamps/cm 2 .
Claim 5
Dependent Claim
17 words
A method according to claim 3 wherein the anode has a Quasi-Tafel Constant of at least 400.
Claim 6
Dependent Claim
17 words
A method according to claim 4 wherein the anode has a Quasi-Tafel Constant of at least 500.
Claim 7
Dependent Claim
18 words
A method according to claim 1 wherein the conductive polymer has a resistivity of 1 to 100 ohm.cm.
Claim 8
Dependent Claim
19 words
A method according to claim 1 wherein the conductive polymer contains carbon black or graphite as a conductive filler.
Claim 9
Dependent Claim
22 words
A method according to claim 1 wherein the conductive polymer will pass a current density of at least 10 milliamps/cm 2 .
Claim 10
Dependent Claim
41 words
A method according to claim 1 wherein the anode is in the form of a flexible strip which has a constant cross-section along its length and which consists essentially of the metallic core and the conductive polymer element surrounding the core.
Claim 11
Dependent Claim
58 words
A method according to claim 1 wherein the ratio b+D/a+D is less than 2, where b is the largest distance from the substrate to the electrode, a is the smallest distance from the substrate to the electrode, and D is the largest dimension of the substrate in a plane at right angles to the axis of the electrode.
Claim 12
Dependent Claim
17 words
A method according to claim 10 wherein the substrate is a metal pipe having a diameter D.
Claim 13
Independent Claim
141 words
A method of cathodically protecting metal reinforcing bars encased in a mass of concrete, which method comprises establishing a potential difference between the reinforcing bars as cathode and a distributed anode which lies within the mass of concrete adjacent to the reinforcing bars and spaced apart from the reinforcing bars by concrete, the anode comprising a flexible strip comprising (1) a continuous elongate flexible metal core which has a resistance at 23° C. of less than 0.03 ohm/meter; and (2) an elongate element which (i) is in electrical contact with the core; (ii) is composed of a conductive polymer having an elongation of at least 10% and a resistivity at 23° C. of 0.1 to 10 3 ohm.cm; (iii) provides substantially the whole of the electrochemically active outer surface of the flexible strip; and (iv) is at least 500 microns thick.
Claim 14
Independent Claim
141 words
A method of cathodically protecting metal reinforcing bars encased in a mass of concrete, which method comprises establishing a potential difference between the reinforcing bars as cathode and a distributed anode which lies within the mass of concrete adjacent to the reinforcing bars and spaced apart from the reinforcing bars by concrete, the anode comprising a flexible strip comprising (1) a continuous elongate flexible metal core which has a resistance at 23° C. of less than 0.03 ohm/meter; and (2) an elongate element which (i) is in electrical contact with the core; (ii) is composed of a conductive polymer having an elongation of at least 10% and a resistivity at 23° C. of 0.1 to 10 3 ohm.cm; (iii) provides substantially the whole of the electrochemically active outer surface of the flexible strip; and (iv) is at least 500 microns thick.
Claim 15
Dependent Claim
30 words
A method according to claim 12 wherein the electrode has a Quasi-Tafel Constant of at least 300 millivolts/decade over a current density range of 1 to 500 microamps/cm 2 .
Claim 16
Dependent Claim
17 words
A method according to claim 13 wherein the electrode has a Quasi-Tafel Constant of at least 400.
Claim 17
Dependent Claim
30 words
A method according to claim 12 wherein the conductive polymer has a resistivity of 1 to 100 ohm.cm and the conductive polymer contains carbon black or graphite as conductive filler.
References Cited (Backward Citations)
US1842541A
Cited
US2020844A
Cited
US2053214A
Cited
US2491225A
Cited
GB875892A
Cited
US3022242A
Cited
US3151050A
Cited
US3332867A
Cited
US3260661A
Cited
US3410772A
Cited
US3391072A
Cited
US3349017A
Cited
US3354063A
Cited
US3498898A
Cited
AU2921167A
Cited
US3623968A
Cited
NL7010559A
Cited
US3798142A
Cited
JPS4834293B1
Cited
US3868313A
Cited
GB1394292A
Cited
US3887449A
Cited
US4098967A
Cited
US3977956A
Cited
US4091291A
Cited
US4186075A
Cited
JPS5348948A
Cited
GB2008616A
Cited
DE2839085A1
Cited
US4196064A
Cited
WO1980001488A1
Cited
EP0014030A1
Cited
GB2046789A
Cited
US4255241A
Cited
GB2053973A
Cited
US4267029A
Cited
US4339325A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-03-04 | 1988-09-03 | 1989-03-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-03-04 | 1992-09-03 | 1993-03-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-03-04 | 1996-09-03 | 1997-03-05 | $7700.00 | Window Closed / Lapsed |